Just removing the font-weight: 300 helps tremendously. Personally, I'm becoming less of a fan of external fonts. I've noticed lately that they're often the slowest thing to load on sites that use them (especially Google fonts).
It's painfully thin, and the eyestrain factor is pretty high.
Original: working on a standard DPI Mac, but it still looks fine - see http://imgur.com/WRWYzBx. Trying to figure it out now...
Cause that looks like a printer that ran out of ink.
But you don’t notice it until you open a font selection menu.
But seriously, I had to use Gtk3's font selection menu today, and it was impossible to work with it.